Endocrine Abstracts

Hyperinsulinism has been shown to trigger sympathetic activity experimentally, however the clinical and epidemiologic data on the association of heart rate with hyperinsulinism and insulin resistance. This study was investigated the relationship between insulin resistance and exercise test parameters in unselected consecutive middle aged asymptomatic patients with type II diabetes.

Ninety asymptomatic type II diabetics between the ages 36 and 60 without any documented evidence of coronary artery disease. Duration of diabetes in study group is 4 plus/minus 4,2 years (range from 1 to 21). We used the homeostasis model of insulin resistance (HOMA IR) as a measure of insulin resistance. All patients were subjected to treadmill exercise test with Bruce protocol. Four subjects were tested positive (4,4 %). According to HOMA IR index, patients were separated to three groups; Group I (n:20) HOMA IR index < 2, Group II (n:37) index 2-3,99 , Group III (n:33) index > or = 4.

Group III has higher body mass index (p=0.000, p=0.001), baseline (p=0.007, p=0.02), peak (p=0.003, p=0.03) and rest (3.min) (p<0.05, p=0.03) systolic blood pressures, peak double-product (p=0.001, p=0.03), delta double-product (peak-baseline) (p=0.03, p=0.02) than group I and II. Also Group III has higher cardiovascular risk factor (p=0.000) and fibrinogen level (p=0.02) than group I. BMI. We found a lot of significant correlation between HOMA IR index and exercise test parameters.

Elevated heart rate and blood pressure have been predictive of cardiovascular disease and cardiovascular mortality. Elevated heart rate and blood pressure may reflect a shift in autonomic balance toward enhanced sympathetic and suppressed vagal tone. We suggested that increased insulin resistance is related higher baseline, peak and rest exercise parameters due to enhanced sympathetic tone.